Network security devices typically limit access to network resources based on various authentication procedures designed to limit access to only authorized users executing approved applications. One problem with granting access to a client device in this manner is that it typically takes considerable processing resources to determine whether the client device is an authorized user executing an approved application. In addition, conventional authorization procedures do not scale well for high speed networks.
Accessing a web page via the Internet is an example of a type of network activity that may be subject to screening by a network security device. When a user accesses a web page (or web site) through a local browser application (e.g., Internet Explorer, Netscape, FireFox, etc.), the application downloads content corresponding to the web page and renders (displays) the web page. A web page generally includes one or more constituent files (e.g., inline objects) that represent individual components (e.g., images, frames, text, etc.) making up the complete web page as displayed by the browser application. Each inline object, including the web page itself, is identified by a uniform resource locator (URL) that uniquely identifies the location of the web page on the Internet. Web pages are generally coded in hypertext markup language (HTML). In order to display a web page, the browser application first requests the web page content, and then parses the HTML associated with the web page to gather references to remaining URLs and instructions for displaying the web page. The browser application executes requests required to obtain remaining inline objects necessary to display the web page.
A measure of how long it takes for a web page to be displayed may be referred to as the response time of the web page or a web page download response time. The web page download response time may be a function of cumulative response times (e.g., inline object response times) associated with inline objects that constitute the web page. A web page may be accessed via an Internet protocol, such as hypertext transfer protocol (HTTP). The most common version of HTTP in use today is HTTP Version 1.1 (or HTTP 1.1). HTTP 1.1 operates over a transport layer provided by a transport control protocol (TCP). HTTP 1.1 distinguishes itself from HTTP 1.0, an earlier version of HTTP, primarily in that it can use the same TCP connection to query one or more inline objects. For HTTP 1.0, a separate TCP connection was established for each individual inline object query. However, HTTP 1.1 may depend on the implementation of particular web browsers and the strategy used by web browsers to group the connections.